操作系统信息
sysadmin@linux01:~$ cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=13.04
DISTRIB_CODENAME=raring
DISTRIB_DESCRIPTION="Ubuntu 13.04"
sysadmin@linux01:~$ uname -a
Linux linux01 3.2.0-38-generic #61-Ubuntu SMP Tue Feb 19 12:18:21 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
sysadmin@linux01:~$ free -m
total used free shared buffers cached
Mem: 3887 3462 424 0 104 1172
-/+ buffers/cache: 2186 1701
Swap: 15259 0 15259
硬件信息
id: firmware
description: BIOS
vendor: Intel Corp.
physical id: 0
version: TCIBX10H.86A.0037.2010.0614.1712
date: 06/14/2010
size: 64KiB
capacity: 960KiB
capabilities: pci upgrade shadowing cdboot bootselect socketedrom edd int13floppy1200 int13floppy720 int13floppy2880 int5printscreen int9keyboard int14serial int17printer acpi usb biosbootspecification
id: cpu
description: CPU
product: Intel(R) Core(TM) i5 CPU 760 @ 2.80GHz
vendor: Intel Corp.
physical id: 4
bus info: cpu@0
version: Intel(R) Core(TM) i5 CPU 760 @ 2.80GHz
id: memory
description: System Memory
physical id: 28
slot: System board or motherboard
size: 8GiB
id: bank:0
description: DIMM DDR3 Synchronous 1333 MHz (0.8 ns)
product: JM1333KLN-4G
vendor: Undefined
physical id: 0
serial: 0009B06F
slot: CHANNEL A
size: 4GiB
width: 64 bits
clock: 1333MHz (0.8ns)
id: bank:2
description: DIMM DDR3 Synchronous 1333 MHz (0.8 ns)
product: JM1333KLH-4G
vendor: Undefined
physical id: 2
serial: 0009EA2B
slot: CHANNEL B
size: 4GiB
width: 64 bits
clock: 1333MHz (0.8ns)
来自 dmidecode 的附加信息
# dmidecode 2.11
SMBIOS 2.6 present.
79 structures occupying 3163 bytes.
Table at 0x000E9270.
Handle 0x0000, DMI type 0, 24 bytes
BIOS Information
Vendor: Intel Corp.
Version: TCIBX10H.86A.0037.2010.0614.1712
Release Date: 06/14/2010
Address: 0xF0000
Runtime Size: 64 kB
ROM Size: 1024 kB
Characteristics:
PCI is supported
BIOS is upgradeable
BIOS shadowing is allowed
Boot from CD is supported
Selectable boot is supported
BIOS ROM is socketed
EDD is supported
5.25"/1.2 MB floppy services are supported (int 13h)
3.5"/720 kB floppy services are supported (int 13h)
3.5"/2.88 MB floppy services are supported (int 13h)
Print screen service is supported (int 5h)
8042 keyboard services are supported (int 9h)
Serial services are supported (int 14h)
Printer services are supported (int 17h)
ACPI is supported
USB legacy is supported
BIOS boot specification is supported
Targeted content distribution is supported
Handle 0x0028, DMI type 16, 15 bytes
Physical Memory Array
Location: System Board Or Motherboard
Use: System Memory
Error Correction Type: None
Maximum Capacity: 16 GB
Error Information Handle: 0x0029
Number Of Devices: 4
Handle 0x002B, DMI type 17, 28 bytes
Memory Device
Array Handle: 0x0028
Error Information Handle: 0x002C
Total Width: 64 bits
Data Width: 64 bits
Size: 4096 MB
Form Factor: DIMM
Set: None
Locator: CHANNEL A
Bank Locator: CHANNEL A-DIMM 0
Type: DDR3
Type Detail: Synchronous
Speed: 1333 MHz
Manufacturer: Undefined
Serial Number: 0009B06F
Asset Tag: A1_AssetTagNum0
Part Number: JM1333KLN-4G
Rank: 2
Handle 0x0031, DMI type 17, 28 bytes
Memory Device
Array Handle: 0x0028
Error Information Handle: 0x0032
Total Width: 64 bits
Data Width: 64 bits
Size: 4096 MB
Form Factor: DIMM
Set: None
Locator: CHANNEL B
Bank Locator: CHANNEL B-DIMM 0
Type: DDR3
Type Detail: Synchronous
Speed: 1333 MHz
Manufacturer: Undefined
Serial Number: 0009EA2B
Asset Tag: A1_AssetTagNum2
Part Number: JM1333KLH-4G
Rank: 1
从以上信息可以看出，lshw我的系统可以释放 8GB RAM，但操作系统不能。这是一个 64 位系统。我尝试运行 Live CD，但没有成功。我还安装了最新的内核，执行了升级 grub 并检查了 /etc/default/grub 配置文件。没有问题。
我也升级了 BIOS。
有人能帮忙解决这个问题吗？
答案1
可能是 (某些 DDR-)-RAM 比您机器的 BIOS 更新。这意味着 BIOS 无法正确识别您的 RAM - 因此该 RAM 对 Linux 而言是“不可见的”。BIOS 更新可能会有所帮助。
还忽略了一点：可能是您的主板不允许超过 8 Gibi？！所以额外的 4 Gibi 不起作用。请咨询您的主板生产商。